104 THE MYOLOGY OF THE RAVEN. 



posterior moiety of the belly of this muscle into two 

 portions, covered by separate sheaths of fascia, but in 

 the smaller and anterior division the fibres again come 

 together and are included in the same sheath. 



In the Apteryx this muscle has very much the same 

 origin and insertion that it has in the Eaven. Ac- 



o 



cording to Mivart it "is generally in Mammals much 

 as it is in the human subject. It may be considerably 

 smaller, however (as in Cetaceans) ; and by a singular 

 exception it may (as in the Echidna) exclusively arise 

 from the external surface of the scapula " (Elem. 

 Anat., p. 326). 



The subscapularis is a powerful rotary muscle of the 

 head of the humerus, and also an important auxiliary 

 in retaining that bone in its shallow facet, and pre- 

 venting displacement. 



66. The serratus parvus anticus a is a thin, flat muscle 

 covering the outer parietes of the chest. It arises by 

 three rather extensive digitations from the outer surfaces 

 of the first free rib, and the next two succeeding ones 

 that connect with the sternum, above the origins of the 

 serratus magnus anticus and the tlwraco-scapularis. 

 The fibres in a flat sheet of fascia pass upwards and back- 

 wards, to become inserted in the inferior margin of the 

 corresponding scapula, along a line to the outer side of 

 the insertion of the rhomboideus, as indicated in Fig. 8. 

 In the Penguins this is the largest of the muscles of the 

 scapula. 



In the Eaven at least, the levator scapulae, the 

 serratus parvus anticus, and the serratus magnus 

 anticus, all really belong to the same system or series, 



1 See footnotes and synonymy under muscles described in the 

 present work as the serratus magnus anticus and the thoraco- 

 scapularis (Nos. 59 and 64). 



